A Coadjutor of Strange Cause
by Alatar Maia
Summary: Fifth in the Strange series. Arachne fell, but she wasn't the only one who got sent down a pit with a one-way link to Tartarus. And then, quite suddenly, Percy and Annabeth had more of a chance than anyone thought they would. Not that they're going to do something smart with it, of course.


**So I'm sure you all know who's appearing here...and yet no one managed to figure out who would come after this! I'll give you a hint; it doesn't exactly fit with the pattern so far...**

 **Moving on! This takes place right at the beginning of the House of Hades. I'm sure you all remember what happened at the end of Mark of Athena, and this is related to that, but I had to move onto the next book so as not to break pattern. With the one-story-per-book thing, anyway. And let me say [since I just reread it] that Rick Riordan dealt with Percy and Annabeth's post-Tartarus mentalities _horribly._ Seriously? They acted exactly the same? No trauma at all? Give me a break.  
**

 **Disclaimer: I do not own Heroes of Olympus.**

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After all that had happened to him that day, Percy hadn't expected to land on what felt like smooth stone.

He'd fallen into _Tartarus._ He was expecting every horrible thing the world had to offer. The worst monsters the dankest pit of the Underworld could drum up. Maybe the Minotaur, again. The Fates seemed to enjoy making _that_ monster crop up in his path. he had expected pitch blackness, maybe evilly glowing fires. Screaming, all that good stuff. Dark walls and creepy, misty surroundings probably fit into there somewhere, but...

Wherever in Tatarus he was, this seemed kind of tame for the pit reserved for the really evil stuff.

Next to him, Annabeth groaned. Her backpack was on the ground next to her, its contents partially scattered. They'd probably fallen out as they were plummeting to their doom. Her bronze knife glinted in the dull light that didn't seem to come from anywhere in particular.

It was very grey. That was about all Percy could make out, and really the best way to describe it. It was a very dark and morose grey, but grey nonetheless.

His whole body felt sore - but that made sense, considering how far they'd fallen. It seemed like it had taken ages for them to hit the ground. Percy didn't know how far they were underground, but it was probably a distance that couldn't be measured by conventional methods.

"You know," a vaguely feminine voice said, startling Percy. "You're very fortunate it was the two of you and not just one who fell. I might not have gotten you in time otherwise."

Percy managed to drag himself to his knees. They'd been here three seconds and there was already something (probably) trying to kill them. Annabeth was already reaching for her knife. A shoe appeared out of the grey misty stuff that was all around them and kicked it away from her hand. It partially vanished, the fog-stuff obscuring it and turning it into a vague, slightly darker shape.

The shoe revealed itself to be attached to a person, who was wearing a long skirt that it vanished under. The person's upper body, however, was still mostly obscured. Percy couldn't make out any more than the vague outline of their body.

"There's no need for that." The voice was definitely coming from the figure.

"Who are you?" Annabeth demanded. She was sitting upright, but Percy could see her shaking almost imperceptibly.

"You cannot guess?" The figure tutted. "Think, demigods. Who among my kind has cause to help you?" The figure was holding a staff, and she used the end of it to poke Annabeth's shirt where the faded pegasus of Camp Half-Blood was still imprinted. The hand holding it was hidden in a leather glove, but from what Percy could make out their other hand wasn't. Maybe they had lost one.

"We're in Tartarus," Percy said. "There's no way anything could be down here but monsters, and none of _them_ would help us."

The figure sighed heavily and muttered something Percy couldn't make out. "Are you, truly, in Tartarus? Look around yourselves. Use your eyes, demigod."

"Where else could we be but Tartarus?" Annabeth asked.

"You know of no one who might be able to rescue you from that fate?" the figure asked, and Percy could see the minute it clicked in Annabeth's brain.

She inhaled sharply. "You're Hel," Annabeth said.

"Hell?" Percy asked, confused. How could a person _be_ Hell?

"Goddess of the Norse underworld." Annabeth was staring up at the person's invisible face. "You...we're in Niflheim. Right?"

"You are in Helheim," the figure - Hel - corrected her.

"But-" Percy couldn't wrap his head around it. "We were falling into Tartarus. There's no way-"

"Tartarus is only another dead realm," Hel interrupted him. "All realms of the dead are interconnected, in one way or another. I merely pulled you into mine through that connection before you escaped my grasp. You're welcome for that, by the way."

Annabeth hesitated. "Thank you," she said. Hel seemed satisfied with that.

Percy was elated for all of a second before his mood plummeted. "The Doors," he said, and Annabeth turned to look at him. "I - they're still open." He pushed himself to his feet, ignoring how his entire body protested moving. "The Doors of Death are still open. We can't close them unless someone helps from the Tartarus side."

"And?" Hel asked.

"And-" Percy was nonplussed. "Well - can't you help us?"

He caught a glimpse of a stiff smile. "I already have, demigod. Do you assume that it is easy to reach between the realms of the dead and draw someone back across? Especially when they still live, and do not belong to me? I have repaid my family's debt to you. I can give you a way back into the realm of the living, but that is where my aid ends."

"If Gaia rises, it will affect everyone," Annabeth argued. "Even you. She won't want any gods around at all, whether they're Greek or not!"

Hel moved forwards sharply through the fog, her face coming into clear view, and Percy had to fight not to react. Half her face was _mummified,_ dead and stiff, while the other half was perfectly alive. One eye was narrowed - the other was hidden under an eyelid that looked unlikely to open.

"With my father around," Hel said to the two of them, "I highly doubt it."

"He can't stop it on his own," Annabeth managed.

Hel's mouth curled in a grin - or at least, the living half of it did. "You underestimate an archangel's power. He could rewrite reality if he so wished, so that your Gaia never existed, if it would not attract so much attention from those he wishes to avoid."

The idea that Loki - _Gabriel_ \- could make Gaia just disappear was staggering. Percy stood firm. "If he won't do it," he said, "then we've got to. And the only way to do that is to close the Doors of Death."

Hel studied him intently. "The only way to close them, if what you say is true, would be for you two to truly enter Tartarus."

"What if you-" Annabeth began.

" _No._ " Hel's sharp reply startled Percy. "I will not go into Tartarus. I do not belong there, nor do I wish to so much as catch a glimpse of the place." Her posture was stiff and unyielding. "You ask too much of me."

"Then help us get there." Annabeth was standing unsteadily on her broken ankle, but her makeshift splint had held up surprisingly well.

"You would not survive."

"It's the only way," Annabeth said, a touch desperately. "Please. We have to do this. We'll find a way to survive."

Hel looked at them flatly. "You have a very high opinion of your own skill."

"For a reason," Percy said, and it was true. He hadn't been keeping himself alive on skill, adrenalin, and luck since he was twelve for nothing.

Hel made a noise that sounded a bit like a sigh. "If you are determined to kill yourselves, then I suppose there is nothing I can do." She used the end of her staff to push Annabeth's knife back towards her. The backpack received similar treatment, except Hel pulled it towards herself.

"Hey-" Annabeth made to move towards the goddess and then froze, her ankle abruptly making itself known again. " _Ow-_ "

"Be calm." Hel dug into the backpack, pulling out something very familiar. "I was only looking for this."

Percy frowned at the globe of light, turning towards Annabeth. "You took it off the ship?"

"It's supposed to ward off monsters," Annabeth grumbled. "Leo said he didn't mind."

Hel tapped it, and the red light inside glowed black for a moment. Percy wasn't sure how something could glow _black._ His eyes didn't seem to want to process it. But the color faded almost immediately, returning to a (slightly darker) red.

"What did you do?" Percy asked.

Hel tossed the ball at him, and Percy caught it reflexively. "I changed its purpose," she said. "It is impossible to avoid monsters and demons in Tartarus; you would only end up attracting more."

"So what does it do now?" Annabeth was staring at the sphere curiously.

Hel smiled her strange half-smile again. "It will lead you to places where you can find help," she said. "Or whatever sort of aid two demigods might be able to find in Tartarus. There may be none, but half a chance is better than no chance."

Percy glanced at Annabeth, who seemed to have steeled herself. "Thanks," he said. "Really."

"Don't thank me," Hel said. "If you were Norse, I'd be seeing you again very soon." She paused, as if to think. "Then again, unless some monster sneaks up on you by chance, perhaps not."

She slammed her staff to the ground, and the floor fell away under Percy's feet.

They fell.

Again.

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 **Ehehehehehehehehehehehehehe**

 **Read and review, please.**


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